mmg_233_2014_genetics_genomicsfandomcom-20200215-history
The Central Dogma of Molecular Biology
The Central Dogma of Molecular Biology is the overall notion that: DNA is transcribed into RNA, which is then translated into proteins. This idea was first brought into light by Francis Crick in 1956[9. This seemingly simple scheme is the genetic process behind making proteins, which in turn, make up the basis of all living organisms and control all processes within them, both structural and enzymatic[1]. In the sections to follow, the individual steps of the central dogma of molecular biology will be explained in further detail and then combined back together to summarize the idea as a whole. DNA Replication: DNA can be thought of as the blueprints for making every type of protein within an organism. It is replicated in order to preserve itself (semi-conservative replication) and to pass the organism's genetic information onto newly manufactured cells. When cells are about to divide, they need to replicate their DNA in order to pass the information to both of the newly formed cells. This is done by first clipping the DNA double helix (DNA gyrase), and then unwinding the DNA (helicase) to form two complementary strands. Once the two complementary strands are formed they are held open by proteins called single strand binding proteins or SBB. The main replication process then occurs through the actions of another enzyme (DNA polymerase) which travels along the now single-stranded DNA strands and pairs up the existing bases with their complementary base pairs (Adenine with Thymine, Cytosine with Guanine) to form new nucleotides[3] . Once the new DNA is formulated, the strands are proofread in order to eliminate any errors in the replication process. Lastly, a final enzyme (DNA ligase) seals the fragments into one continuous strand and then combines the two newly formed strands, which then wind back into the double helix structure[3]. DNA Transcription: 7]]] DNA transcription is the process of transcribing DNA strands into RNA. This process is carried out by a similarly named enzyme to the DNA replication process, called RNA polymerase. RNA polymerase will attach to a DNA segment and begin constructing a complementary RNA strand from the DNA. The process is similar to the DNA replication process, but this time the base pairs that are matched up are adenine-uracil and guanine-cytosine. Notice that in RNA, thymine is replaced with uracil[5]. The three steps of the transciptionn process are: initiation, elongation, and termination. First the RNA polymerase initiates the coding by attaching to the DNA segment at what is called the "promoter region". Then the coding process occurs, similarly to the DNA replication process, by RNA polymerase walking along the DNA segment and matching up base pairs. Lastly, the process is terminated by what is called the "terminator sequence," which is at the end of the coding sequence[5] . The final product is a newly made strand of mRNA (messenger RNA), which can then be translated into amino acid chains, otherwise known as proteins. RNA Translation: The overall mission of RNA translation is to translate the mRNA strand into amino acid chains, which when complete will form a specific protein. The genetic code of the mRNA is read by a molecule called a ribosome in sets of three letter combinations of nucleotides, otherwise known as codons. Once a codon is translated by the ribosome, a molecule called tRNA (transfer RNA) will carry in a specific amino acid and add it to the chain being formed. Going along the mRNA strand until the end, the ribosome builds long amino acid chains. Once a chain of amino acids is completely assembled, it is then called a protein[6.] . Summary The Central Dogma of Molecular Biology is the idea that DNA is replicated, transcribed into mRNA, and then translated into amino acid chains that are called proteins. Proteins are the basis of all living matter, and they literally control all of the processes that occur within living organisms. All of the proteins needed to run the human body are within the DNA of every cell within the body and through replication, transcription, and translation, any protein can be made at any time[6. References: # The Central Dogma of Molecular Biology by National Health Museum # Central Dogma by Biology.tutorvista.com # How DNA Works by Craig Freudenrich # DNA Replication by Natasha Javeri # DNA Transcription by Suzanne Clancy # Translation/RNA Translation by Nature Education # Primary Transcript by Wikipedia.org # Translation Overview by About.com # Central Dogma of Molecular Biology by Wikipedia.org